Calories come from macronutrients, which many of you may know as carbohydrates, proteins and fats. Macronutrients differ from micronutrients in major two ways: they are required in large amounts by the body and provide energy. Micronutrients are required in much smaller amounts (hence the micro-) and have important structural and functional roles but don’t provide energy.A diet balanced in these three macronutrients is important for meeting the body’s broad needs. For example, carbohydrates largely fuel our brains and physical activity, proteins are used to build and maintain lean muscle, and dietary fats contain important building blocks for all cells in the body.You’re probably well aware that consuming too many calories leads to weight gain. Eat too many calories from any of the 3 macronutrients, and they’ll be converted to fat. Conversely, consume fewer calories than you expend and those fat stores will be used up to produce energy. Weight maintenance is the fine art of energy balance.It seems very calculated but equating calories to pounds of fat is really just a scientific approximation.Here’s a quick overview of the math:

1 pound of fat tissue weighs 454 grams – fact.

Approximately 87% of fat tissue (or 395 grams) is actually fat. The composition of fat tissue may vary slightly from person-to-person, and study-to-study.

1 gram of fat provides about 9 calories of energy, though it could be anywhere in the range of 8.7 – 9.5 calories per gram according depending on which journal article you read.

395 grams of fat at 9 calories per gram adds up to 3,555 calories per pound of body fat, which is again rounded to 3,500 for ease of calorie counting. 1 pound is roughly equivalent to 0.45 kilograms or 0.07 stone.